Headphone noise cancellation "slosh"


Got the new headphones a week or so ago and am duly impressed by the price/performance. One question: I know that noise cancellation can add a “slosh” or swishing sound to the silence in music. I listen to quiet music like piano and other instrumental works and there can be a blurring or slurring or smearing, actually that’s the word, a smearing of the sound, presumably from the noise cancellation.

Is this adjustable (other than turning it off)?